A damaged tube of a tube heat exchanger has traditionally been repaired by plugging the damaged tube at the end plates. The plugging has most commonly been made by closing the ends of the tube by welding, whereby the heat exchange medium cannot flow through the damaged tube. In tube heat exchangers having several tubes, plugging one or a few tubes has however not essentially affected the efficiency of the heat exchanger.
A repairing method for a plate heat exchanger has been presented, i.a. in patent publication WO 2012011866, where the plate space adjacent to a damaged plate is closed by pumping filling material between the plates. Thereby the leaking point in the plate has been closed with the material, but the plate space filled with the material is thereafter no longer usable.
Plate heat exchangers of the Plate&Shell-type comprise a plate pack formed of heat exchange plates having openings, in which plate pack the heat exchange plates are attached to each other as plate pairs, the inner parts of which plate pairs are arranged in connection with each other via flow channels formed by the openings of the heat exchange plates. A primary circuit of the heat exchanger is formed of the flow channels formed by the openings of the heat exchange plates and the inner parts of the plate pairs that are in connection with these flow channels. An outer casing of the heat exchanger surrounds the plate pack. A secondary circuit of the heat exchanger is formed of the shell part of the heat exchanger, which shell part is in connection with the spaces between the plate pairs of the plate pack. Problems may arise in such Plate&Shell-type heat exchangers when leaking points are formed in the flow channels passing through the plate pack or in the middle parts of the plates of the plate pack. The plate spaces or the flow channels cannot be easily fixed due to the fully welded structure of the heat exchanger.